I highly recommend finding a Samsung Syncmaster 215TW (22 inch) It rotates and has PIP and HD capabilities. The retail is about 500 but I got a killer deal at Office Max for only 235. Check that store often they have the craziest rebate combo mania deals of all time. I have a dual monitor setup and I like it. My other monitor is an emachines widescreen 19 inch (I get overlap on the 19 but it's not a big deal). I usually 6 or 8 table and they work great. I don't remember the video card I bought but it has dual PCI slots.
Also it is nice to have 2 monitors to play poker on one and browse the internet on the other.